Process of and apparatus for recovering paraffin



.March 2 7, 1928.

= w. A. GRUsE E1' AL PROCESS 0F AND APPARATUS FIOR REGOVERING ARAFFIN 2 Sheets-Sheet 1 Filed Oct. 28. 1924' March 27, 192s. 1,663,592

W. A. GRUSE ET AL PROCESS 0F AND APPARATUS FOR RECOVERING PARAFFIN Filed oct. 28. 1924 2 sheets-Shah 2 Patented Mar. 27, 1928.

'UNITED' STATESv 1,663,592 PATENT OFFICE.

'WILLIAM A. GRUSE, OF WILKINSBURG', AND 'WARREN F. FARAGHER, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNORS TO" GULF REFINING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF TEXAS.

APRGESS OF AND APPARATUS FOR RECOVERING- PARAFFIN.

Application iled October 28, 1924. Serial No. 746,34.

This invention relates to processes of and apparatus for recovering paraiiin; and. 1t comprises a continuousmethod of making hard paraffin wherein a solidified mass of 5 paraifin or paraiiin oil is conveyed under the surface of a body of water of a xed temperature, being cut and commingled y"repeatedly during its progress; and it further comprises as a new assemblage of apparatus elements for the recovery of hard paraiiin a water tank, means for keeping water therein of uniform predetermined temperature, intermeshing twin screw conveyor means withinl said tank, means for delivering par-l ain or parafin oil to one end of screw conveyor-means, means for removing relatively hard paraiin from the other end and means for removing ioated paraiin oil or relatively soft parain from the surface of the water in said tank; all as more fully hereinafter set forth and as claimed.'

Paraftin wax as it is recovered from high boiling petroleum distillates is a complex of very many Asimilar waxy hydrocarbons o f varying melting points. In practice, it le usual to recover it by chilling an appropriate distillate containing wax to'such a temperature that the wax crystallizes out, rendering the total distillate a semi-solid mush. This mush is pumpedto filter presses, which separate the solid paraiiin wax from the liquid oil, giving a cake of wax. Acertain amount of wax of such low melting point that it is normally liquid at ordinary temperatures and a certain amount of liquid oil are retained in the filter cake of wax crystals. The material thus recovered as a filter cake is known as slack wax. This slack wax is melted and cooled slowly to solidify in con- 40 venient cakes which are placed on draining racks. These racks are located in pans and ture of the air in the space around the pans will eect, first a separation and draining ofi.' of the occluded liquid oil and of the lowest melting wax', then a fractional fusion of the next lowest melting wax, with subsequent draining and separation. By appropriate removal of liquefied material from the pans, and by continuing to raise the temerature various fractions-may be obtained. o obtain products of more denite melting point the process may be repeated a number point we vary the procedure.

of. times. In commercial practice, the operation 1s unduly time consuming and requires considerable apparatus as well as chamber space in order to make goodv grades n of wax of various melting points` .It 1s the purpose of the present invention to provide a simpler and quicker and more economical process of making fractions of wax of various melting points. To this end the process is made a continuous one; solidilied paraiiin orpar aiiin oil being continuously fed into one end of the apparatus and a 'wax fraction of desired melting point being continuously removed at the other.

In the. present invention the wax which is to be separated or the wax distillate is melted and cooled as usual to a definite temperaturewhereby some portion of the wax crystallizes and the -material is pressed. This is the usual operation so far but at this The Vcaked material of mixed solid and liquid or vslack wax is fed to a pair of intermeshing screw `conveyors located in a tank of water of and'intermingling which is erformed the solid .is quite effectively free of the'li uid.

Parafin wax at these temperatures-win e it crystallizes, is in a condition in which the crystals will weld together readily and cut surfaces reunite. In the described operation the crystals are cut up and welded together again so to speak and the final product is a solid mass of paraiiin effectively freed of all waxes which are liquid at the temperature of the water bath. 'Ihe operation is very quick and is continuous.

The process may be repeated, the solid Wax delivered bein put through another water bath of somewhat higher temperature or the aov delivered oils and low melting waxes being -recooled and retreatedl in another bath of tion the waxes which it is desired to remove from Jthe hard paraiin. By raising or low- `molten wax and oil. `may be, and advantageously is, lagged or ering the temperature, the paraffin maybe freed of'such constituents as are liquid at the temperature of the bath. f

In the accompanying illustration we have shown, more or less diagrammatically, certain apparatus within the present invention and useful in the performance of the de. scribed process. In this showing,

Figure 1 is a central longitudinal section of a complete apparatus; and Y Figure 2 is a transverse section of the same along lines 2-2 of Figure 1. In this showing element 1 is a water tank of suitable material such as steel or iron. It may be of any size or dimensions but is .advantageously relatively large. Within it water stands at a normal level 2.- Water can be added through inlet 3 and removed at outlet 4, when there is any necessity for freplenishing or cleaning. At the normal water level is valved outlet 5 for removing The whole apparatus otherwise insulated against loss of heat. The temperature may be kept at any point desired by heating coils 6. Agitating means 7 are provided for keeping the liquid in the tank of uniform temperature. downward through the body of water in the tank is conveyor casing '7a containing screw conveyor 8. At the top is hopper 9 for receivin paran wax. The screw conveyor forces te cake downward and breaks it up, delivering it, as shown by the arrow, to a horizontal conveyor casing 10 of perforated meta-l. This casing contains, as best seen in Fig. 2, a pair of twin screw conveyors 11 and 12 which intermesh. Above lthe conveyor 'casing is a deiector plate 13, (see Fig. 2) serving to/conduct oil expelled in the casing to the side; As shown, the twin conveyors force the cake throu h the warm water to the right. .As the ca e 1s cut up by the action of the conveyors expelled oil rises,

finds its way through the perforated casing and ultimately gains-access to the surface of the water 1n the bath. The cut-up cake arriving at the right goes upwardly to a similar pair of conveyors 14 also located in a perforated or slotted metal casin The conveyors 14 cause the cake to trave to the left. At the end of its period of travel it is again taken to the right by similar conveyors 15, again to the left by conveyors 16 and finally rby conveyorsl'? to a receiving chamber 18, whence it may be removed from the apparatus by any suitable conveyor diagrammatically indicated at 19. v

, The oil and molten wax separated from the hard paraiin Vwax by floating on the Passing water pass out through the pipeline 5. The chamber 18 may be provided with a closed vtop if desired. Ordinarily the layer of molten wax and oil does not rise above the top of chamber 18 because outlet 5 acts to keep the molten wax and oil level just below the top of 18. In order to insure no intermin ling of oil with `the hard wax collected in c amber 18, the vertical walls of 18 may be substantially increased in height above the plane of outlet 5. Ordinarily, however, if outlet 5 is disposed slightly below the top of chamber 18, as shown, there will be no tendency for molten wax and oil to get into chamber 18.

For clearness of illustration supports for the casing and shafting have been omitted. These elements may be supported and held in any usual way. The shafts driving the various conveyors may be actuated by any source of' power (not shown).

The operation of the device illustrated is believed to be obvious from the foregoing description.

What we claim is 1. In a continuous method of recovering hard parafhn wax from solidified slack wax, the process which com rises continuously conveying such a solidi ed wax through a body of water of adjusted temperature and during its progress repeatedly cutting the wax in such a manner as to expose all surfaces to the water and allow oil to separate therefrom and to rise through the water.

2. In a continuous method of recovering hard paratn wax from solidified slack wax, the process which comprises conveying such a solidified wax beneath the surface of a body of water of adjusted temperature and durin its progress -continuously cutting, lnea ing and rewelding the wax while allowing `separated liquid to rise through the water, and separately collecting the kneaded wax and the separated molten matter.

3. In a paraflin recovery apparatus, a tank adapted to contain water, means positioned at the normal liquid level of said water to remove oil and molten wax from the surface of said water, a plurality oftwin intermeshing screw 'conveyors within the tank and located below the vnormal water level, means for introducing parain wax at one end of the system of screw conveyors, means for removing puriied -parain wax at the other end, and means for maintaining the water within the tanky at a definite temperature.

In testimony whereof we hereunto aflix our signatures. v "WILLIAM A. GRUSE.

WARREN F. FARAGHER. 

